Hydroxy Ester Pre-Extended Epoxy-Terminated Viscosifiers and Method for Producing the Same

ABSTRACT

Embodiments relate to viscosifiers that are terminated polymers that have functional terminal groups. The polymers being pre-extended by polyepoxides and being reacted to give polymers that are terminated by other functional groups. The viscosifiers have a low content in educts or educt descendants that deteriorate the properties of compositions and considerably reduce or even exclude the formation of high-molecular addition products so that the products obtained have low viscosity and good storage stability.

TECHNICAL FIELD

The invention relates to the field of toughness improvers.

STATE OF THE ART

Polymers have been used as materials for some time. Some polymers,however, have the problem that the polymer matrix fractures on abruptimpact stress, i.e. their toughness is low. Especially polymer matricesbased on epoxy resins are very firm but in many cases not veryimpact-resistant. There have therefore long been attempts to improve theimpact resistance.

This has been attempted for some time now, for example, with the use ofspecific copolymers, which are referred to as so-called liquid rubbers.By virtue of the use of chemically reactive groups, such as hydroxyl,carboxyl, vinyl or amino groups, such liquid rubbers can be incorporatedchemically into the matrix. For example, there have for some timeexisted reactive liquid rubbers butadiene/acrylonitrile copolymersterminated by hydroxyl, carboxyl, vinyl or amino groups, which aresupplied by B. F. Goodrich, or Noveon, under the Hycar® trade name. Thestarting basis used therefor is always the carboxyl-terminatedbutadiene/acrylonitrile copolymer, to which a large excess of a diamine,diepoxide or a glycidyl (meth)acrylate is typically added. However, thisleads to the effect that, on the one hand, a high viscosity forms or, onthe other hand, that a very high content of unconverted diamine,diepoxide or glycidyl (meth)acrylate, which either has to be removed ina complex manner or else significantly adversely affects the mechanicalproperties.

However, the desire in many cases is to obtain even further-enhancedimpact resistance and to have a wider variety of toughness improvers.One such possibility in this direction consists in the chain extensionof epoxy-terminated polymers by bisphenols or by the use of highermolecular weight epoxy resins in the preparation. Here too, according tothe reaction regime, large amounts of unconverted bisphenols or ofextended epoxy resins arise, both of which can quickly adversely affectthe properties of compositions. Moreover, such adducts are rapidly nolonger fluid, as a result of which compositions comprising suchtoughness improvers consequently can no longer be applied in a reliableprocess in many cases. In addition, the use of bisphenols leads toreduced storage stability.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide toughnessimprovers with functional end groups which are capable of alleviatingthe problems of the prior art. The polymers as claimed in claims 1, 11,13 and 14 provide such polymers. They can all be prepared from acarboxyl-terminated polymer as claimed in claim 11, which in turn can beobtained from a readily obtainable carboxyl-terminatedbutadiene/acrylonitrile copolymer. The possibilities which arise fromthe different molecules for pre-extension and termination make possiblea wide range of different toughness improvers, and allow tailoring tothe requirements. The polymers terminated with functional groups havethe great advantage that they have a narrow molecular weightdistribution and a very high proportion of molecules suitable astoughness improvers.

This advantage arises especially through the process for preparing thecarboxyl-terminated polymer as claimed in claim 11, which serves as astarting point for the preparation of the polymers as claimed in claims1, 13 and 14, and especially through the process comprising two stepsfor preparing an end group-terminated polymer as claimed in claim 17.This process as claimed in claim 15 ensures that any unconvertedreactants present are only substances which already act as toughnessimprovers, which likewise react to give reactive toughness improvers inany reaction step leading further to polymer as claimed in claim 1, 13or 14. Therefore, only insignificant amounts, if any, of compounds whichadversely affect the mechanical properties are formed, such thatexceptionally potent toughness improvers can be provided. In spite ofthe many possibilities which arise from pre-extension and epoxytermination, the polymers have an astonishingly low viscosity.

The polymers as claimed in claims 1, 11, 13 and 14 can be used widely asmeans of increasing the impact resistance of a polymer matrix as claimedin claim 18. Particular preference is given to the use thereof in epoxyresin matrix.

Further aspects of the invention relate to compositions comprisingpolymers as claimed in claim 1, 11, 13 or 14, and to cured compositionsas claimed in claims 24 and 25.

Particular preference is given to using such polymers in adhesives,especially heat-curing epoxy resin adhesives. They have exceptionallygood impact resistances.

Preferred embodiments of the invention are the subject-matter of thedependent claims.

Ways of Performing the Invention

In a first aspect, the present invention relates to epoxy-terminatedpolymer of the formula (I).

In this formula, R¹ is a divalent radical of a carboxyl-terminatedbutadiene/acrylonitrile copolymer CTBN after removal of the terminalcarboxyl groups. In addition, R² is a polyepoxide PEP after removal of nepoxy groups and R^(2′) is H or a radical joined to R². In addition, Y¹and Y² are each independently H or methyl. R³ is a diglycidyl ether DGEafter removal of the two glycidyl ether groups. Finally, n is 2 to 4,especially 2.

More particularly, R¹ is a radical as obtained by formal removal of thecarboxyl groups of a carboxyl-terminated butadiene/acrylonitrilecopolymer CTBN sold commercially under the Hycar® CTBN name by Noveon.It preferably has a structure of the formula (IV).

In this formula, the broken lines represent the attachment sites of thetwo carboxyl groups. R is a linear or branched alkylene radical having 1to 6 carbon atoms, especially having 4 carbon atoms, which is optionallysubstituted by unsaturated groups. In an embodiment of which particularmention should be made, the substituent R is a substituent of theformula (VII), where the broken line here too represents the attachmentsites.

In addition, the index q is from 40 to 100, especially from 50 to 90. Inaddition, the labels b and c represent the structural elements whichoriginate from butadiene, and a represents the structural element whichoriginates from acrylonitrile. The indices x, m and p in turn representvalues which describe the ratio of the structural elements a, b and crelative to one another. The index x represents values of 0.05-0.3, theindex m values of 0.5-0.8, the index p values of 0.1-0.2, with theproviso that the sum of x, m and p is equal to 1.

It is clear to the person skilled in the art that the structures shownin formula (IV), and also the further structures shown in formulae (V′″)and (VI′″), should be understood as simplified representations. Theunits a, b and c, or d and e or d′ and e′, may thus each be arrangedrandomly, alternately or blockwise with respect to one another. Moreparticularly, formula (IV) is thus not necessarily a triblock copolymer.

The R² radical is a polyepoxide PEP after removal of n epoxy groups. Anepoxy group is understood to mean a structural element of an epoxiranering

Particularly preferred epoxy groups are glycidyl ether groups

As well as the case in which Y¹ in the latter formula is H, for the sakeof simplicity in the present document, “glycidal ether group” alsorefers to that group of the latter formula in which Y¹ is methyl.

Polyepoxides can be prepared in a known manner, for example, from theoxidation of the corresponding olefins or from the reaction ofepichlorohydrin with the corresponding polyols.

The polyepoxide PEP is a diepoxide, triepoxide or tetraepoxide,especially a diglycidyl ether, triglycidyl ether or tetraglycidyl ether.Such polyepoxides or polyglycidyl ethers are known to those skilled inthe art either as epoxy reactive diluents or else as epoxy resins.

In one embodiment, the polyepoxide PEP is an aliphatic or cycloaliphaticpolyglycidyl ether, preferably an aliphatic or cycloaliphatic diglycidylether, such as

-   -   glycidyl ethers of difunctional saturated or unsaturated,        branched or unbranched, cyclic or open-chain C₂-C₃₀ alcohols,        for example ethylene glycol diglycidyl ether, butanediol        diglycidyl ether, hexanediol diglycidyl ether, octanediol        diglycidyl ether, cyclohexanedimethanol diglycidyl ether,        neopentyl glycol diglycidyl ether, etc.    -   glycidyl ethers of tri- or tetrafunctional, saturated or        unsaturated, branched or unbranched, cyclic or open-chain        alcohols such as epoxidized castor oil, epoxidized        trimethylolpropane, epoxidized pentaerythritol, or polyglycidyl        ethers of aliphatic polyols such as glycerol,        trimethylolpropane, etc.    -   epoxidized dicarboxylic acids such as diglycidyl phthalate and        diglycidyl tetra- and hexahydrophthalate, diglycidyl esters of        dimeric fatty acids, etc.

More particularly, the aliphatic or cycloaliphatic diglycidyl ether is adiglycidyl ether of the formula (V″) or (V′″)

In these formulae, r′ is from 1 to 9, especially 3 or 5. In addition, q′is 0 to 10 and t′ is 0 to 10, with the proviso that the sum of q′ and t′is ≧1. Finally, d′ is the structural element which originates fromethylene oxide, and e′ is the structural element which originates frompropylene oxide. Formula (V′″) is thus (poly)ethylene glycol diglycidylether, (poly)propylene glycol diglycidyl ether and (poly)ethyleneglycol/propylene glycol diglycidyl ether, where the units d′ and e′ maybe arranged in blocks, alternately or randomly.

Particularly suitable aliphatic or cycloaliphatic diglycidyl ethers areethylene glycol diglycidyl ether, butanediol diglycidyl ether orhexanediol diglycidyl ether.

In a further embodiment, the polyepoxide PEP is a polyepoxide which wasprepared from an oxidation of olefins.

Preferred examples of such polyepoxides PEP are those which have atleast one epoxy group and which are prepared via oxidation of acyclohexenyl or cyclohexenylene group.

Preferred polyepoxides PEP of this kind are

and polyesters of polycarboxylic acids and 3,4-epoxycyclohexylmethylalcohol, especially bis(3,4-epoxycyclohexylmethyl)adipate. In theseformulae, v is 2 to 8, and R⁶ and R^(6′) are each independently H or aC₁-C₆-alkyl radical. The indices u and u′ are each 0 to 5, especially 1to 5, with the proviso that u+u′≧1, especially u+u′≧2. Particularlysuitable examples are 3,4-epoxy-cyclohexylmethyl3,4-epoxycyclohexanecarboxylate, bis(3,4-epoxycyclohexyl-methyl)adipate,1,2,7,8-diepoxyoctane, 1,2,3,4-diepoxybutane and1,2,5,6-diepoxycyclooctane.

In a further embodiment, the polyepoxide PEP is an aromatic diglycidylether. These are firstly so-called epoxidized novolacs and secondlyaromatic diglycidyl ethers which, after removal of two glycidyl ethergroups, have an R² radical of the formula (V′).

In this formula, R′″ is independently H, methyl or ethyl, and z′ is 0or 1. It is thus o-phenylene, m-phenylene, p-phenylene, and the derivedstructures thereof which are ring-substituted by methyl or ethyl groups.

In a further embodiment, the polyepoxide PEP is an epoxy resin. Theepoxy resin may be a liquid epoxy resin or a solid epoxy resin.

The term “solid epoxy resin” is very well known to the person skilled inthe art of epoxides and is used in contrast to “liquid epoxy resins”.The glass transition temperature of solid resins is above roomtemperature, i.e. they can be comminuted to free-flowing powders at roomtemperature.

Preferred solid epoxy resins have the formula (VIII).

In this formula, the substituents R⁴, R⁵ and Y² are each independently Hor CH₃. In addition, the index S1 is >1.5, especially 2 to 12.

In this document, the use of the term “independently” in connection withsubstituents, radicals or groups should be interpreted such thatsubstituents, radicals or groups with the same designation may occursimultaneously in the same molecule with different definitions.

Such solid epoxy resins are commercially available, for example from Dowor Huntsman or Hexion.

Compounds of the formula (VIII) with an index S1 between 1 and 1.5 arereferred to by the person skilled in the art as semisolid epoxy resins.For this present invention, they are likewise considered to be solidresins. However, preferred solid epoxy resins are solid epoxy resins inthe narrower sense, i.e. the index S1 has a value of >1.5.

Preferred liquid epoxy resins have the formula (IX).

In this formula, the substituents R⁴, R⁵ and Y² are each independently Hor CH₃. In addition, the index S1 has a value of 0 to 1. S1 preferablyhas a value of less than 0.2.

These are thus preferably diglycidyl ethers of bisphenol A (DGEBA), ofbisphenol F and of bisphenol A/F (the designation “A/F” refers here to amixture of acetone with formaldehyde which is used as the reactant inthe preparation thereof). Such liquid resins are available, for example,as Araldite® GY 250, Araldite® PY 304, Araldite® GY 282 (Huntsman) orD.E.R.™ 331 or D.E.R.™ 330 (Dow) or Epikote 828 (Hexion).

In a particularly suitable form, the radical R² thus represents theformula (V) or (V′).

In these formulae, R′, R″ and R′″ are each independently H, methyl orethyl, z′ is 0 or 1 and s′ is 0 or 0.1-12.

A particularly preferred polyepoxide PEP is bisphenol A diglycidylether.

The R³ radical is a diglycidyl ether DGE after removal of the twoglycidyl ether groups. The options for the diglycidyl ether DGEcorrespond in principle to those for the polyepoxide PEP alreadydetailed as diglycidyl ethers.

More particularly, the diglycidyl ether DGE is an aliphatic orcycloaliphatic diglycidyl ether, especially a diglycidyl ether of theformula (VI″) or (VI′″).

In these formulae, r is 1 to 9, especially 3 or 5. In addition, q is 0to 10 and t is 0 to 10, with the proviso that the sum of q and t is ≧1.Finally, d is the structural element which originates from ethyleneoxide, and e is the structural element which originates from propyleneoxide. Formula (VI′″) is thus (poly)ethylene glycol diglycidyl ether,(poly)propylene glycol diglycidyl ether and (poly)ethyleneglycol/propylene glycol diglycidyl ether, where the units d and e may bearranged in blocks, alternately or randomly.

Particularly suitable aliphatic or cycloaliphatic diglycidyl ethers areethylene glycol diglycidyl ether, butanediol diglycidyl ether orhexanediol diglycidyl ether.

In a further particularly preferred embodiment, the diglycidyl ether DGEis a diglycidyl ether which, after removal of the two glycidyl ethergroups corresponding to the R³ radical, has the formula (VI) or (VI′).

In these formulae, R′, R″ and R′″ are each independently H, methyl orethyl, z is 0 or 1 and s is 0 or 0.1-12.

A particularly preferred diglycidyl ether DGE is bisphenol F diglycidylether.

The epoxy-terminated polymer of the formula (I) can be prepared asfollows:

In a first step (“pre-extension”), a carboxyl-terminatedbutadiene/acrylonitrile copolymer CTBN of the formula HOOC—R¹—COOH and apolyepoxide PEP are used in a stoichiometric ratio (n′≧n) of theHOOC—R¹—COOH to prepare a carboxyl-terminated polymer of the formula(II):

For this reaction, polyepoxide PEP and HOOC—R¹—COOH are used in anamount such that the stoichiometric ratio of the COOH groups to epoxygroups

When this ratio=2, corresponding to n′=n, the trend is toward anincreased proportion of higher molecular weight species, which can leadto significantly increased viscosities in the carboxyl-terminatedpolymer of the formula (II), or in the epoxy-terminated polymer of theformula (I), which can cause problems under some circumstances. At aratio of <2 (corresponding to n′<n), especially of <<2, this problem isvery significantly enhanced. Therefore, a value of >2 is preferred forthis ratio. Typically, a value of >4, in particular >>2, correspondingto n′>>n, is very preferred. In these cases, the reaction mixture has arelatively high content of unconverted HOOC—R¹—COOH. However, this doesnot cause any further problems, as discussed below.

It is clear to the person skilled in the art that it is also possible touse mixtures of polyepoxides PEP and/or carboxyl-terminatedbutadiene/acrylonitrile copolymers CTBN of the formula HOOC—R¹—COOH.

In a second step (“termination”), the carboxyl-terminated polymer of theformula (II) and a diglycidyl ether DGE of the formula (III) are used ina stoichiometric excess (n″≧n) of the diglycidyl ether DGE to prepare anepoxy-terminated polymer of the formula (I):

For this reaction, the polymer of the formula (II) and the diglycidylether of the formula (III) are used in such amounts relative to oneanother that the stoichiometric ratio of the glycidyl ether groups toCOOH groups

When this ratio=2, corresponding to n″=n, the proportion of highermolecular weight species is increased, which can lead to significantlyincreased viscosities in the epoxy-terminated polymer of the formula(I), which can cause problems under some circumstances. At a ratio of <2(corresponding to n′<n), especially of <<2, this problem is very greatlyenhanced. Therefore, preference is given to a value of >2 for thisratio. Typically, a value of >4, in particular >>2, corresponding ton″>>n, is very preferred.

If unconverted carboxyl-terminated butadiene/acrylonitrile copolymerCTBN HOOC—R¹—COOH from the first step is still present in the reactantmixture at the start of this second step, it is reacted in the secondstep to give an epoxy-terminated polymer of the formula (X) known fromthe prior art.

In this manner, it can be ensured that a maximum number ofepoxy-terminated polymers which can be used as impact modifiers arepresent in the final mixture. More particularly, in contrast to theprior art process, the presence of a large molecular weight distributionis prevented, which leads to a deterioration in the applicationproperties, especially a high viscosity.

It is clear to the person skilled in the art that it is also possible touse mixtures of carboxyl-terminated polymers of the formula (II) and/ordiglycidyl ethers DGE of the formula (III). In such a mode ofpreparation, mixtures of epoxy-terminated polymers of the formula (I)form in situ.

In both steps, an ester is formed. Such reactions of epoxides or ofglycidyl ethers with carboxylic acids are known to those skilled in theart, as are the reaction conditions therefor. More particularly,relatively high temperatures, typically temperatures of 100° C.,preferably around 140° C., and optionally catalysts are used, andpreferably under protective gas. Examples of such catalysts aretriphenylphosphine, tertiary amines, quaternary phosphonium salts orquaternary ammonium salts.

Carboxyl-terminated polymers of the formula (II) thus form a furtheraspect of the present invention. The definition, options and preferredembodiments of the radicals and indices shown in this formula (II)correspond to those as have already been described above in detail forepoxy-terminated polymer of the formula (I).

A further aspect of the present invention is a process for preparing acarboxyl-terminated polymer of the formula (II) by a reaction of apolyepoxide PEP with a carboxyl-terminated butadiene/acrylonitrilecopolymer CTBN of the formula HOOC—R¹—COOH, characterized in that thepolyepoxide PEP and HOOC—R¹—COOH are used for this reaction in an amountrelative to one another which corresponds to a stoichiometric ratio ofthe COOH groups to epoxy groups

This process has already been described in detail above in thisdocument.

A further aspect of the present invention is a process for preparing anepoxy-terminated polymer of the formula (I) by the reaction of acarboxyl-terminated polymer of the formula (II) with a diglycidyl etherDGE of the formula (III), characterized in that the polymer of theformula (II) and the diglycidyl ether of the formula (III) are used forthis reaction in an amount relative to one another which corresponds toa stoichiometric ratio of the glycidyl ether groups to COOH groups

This process has already been described in detail above in thisdocument.

It is clear to the person skilled in the art that the epoxy-terminatedpolymers of the formula (I) can be reacted further. For instance, moreparticularly, extension by means of polyphenols, especially by means ofbisphenols, such as bisphenol A, is very helpful under somecircumstances in order to obtain even higher molecular weightepoxy-terminated polymers or phenol-terminated polymers, as represented,for example, in the following formulae (XIII) and (XIV):

In these formulae, the index f is 0 or 1. R⁹ here is H or an alkyl oralkenyl radical, especially an allyl radical.

Further aspects are reaction products formed from thecarboxyl-terminated polymer of the formula (II) with diamines or(meth)acrylate-functional alcohols or glycidyl ether-functional(meth)acrylates, which lead especially to amine-terminated polymers ofthe formulae (XI), (XI′) and (XI″), or to (meth)acrylate-terminatedpolymers of the formulae (XII) and (XII′), according to the followingillustrative reaction scheme:

In these formulae, R⁷ is H or methyl and R⁸ is a divalent radical,especially an alkylene, cycloalkylene or (poly)oxyalkylene radical. Thediamines 1-(2-aminoethyl)piperazine (DA1) or2-methylpentamethylenediamine (DA2) or 1,2-diaminocyclohexane (DA3), andthe glycidyl (meth)acrylate (GMA) and the hydroxy-functional(meth)acrylate (HMA), are each used in a stoichiometric excess, i.e. k,k′, k″, k′″ and k″″ are each greater than n.

The reaction conditions for formation of amides and esters are knownfrom the literature and can be applied to the synthesis of thesereaction products, especially the polymers of the formula (XI), (XI′),(XI″), (XII) and (XII′).

A further aspect of the present invention is thus a process forpreparing an end group-terminated polymer of the formula (XV),

comprising the following two steps:

-   -   a) pre-extension, i.e. reaction of a polyepoxide PEP with a        stoichiometric excess of a carboxyl-terminated        butadiene/acrylonitrile copolymer CTBN of the formula        HOOC—R¹—COOH to give a carboxyl-terminated polymer of the        formula (II) as already described above, in such a way that the        polyepoxide PEP and HOOC—R¹—COOH are used in an amount relative        to one another such that the ratio of COOH groups to epoxy        groups

where the polyepoxide PEP and the carboxyl-terminatedbutadiene/acrylonitrile copolymer CTBN of the formula HOOC—R¹—COOHshould be selected as already described above;

-   -   b) termination, i.e. reacting a carboxyl-terminated polymer of        the formula (II) with a diglycidyl ether or with a diamine or        with a (meth)acrylate-functional alcohol or with a glycidyl        ether-functional (meth)acrylate in such a way that the        diglycidyl ether or the diamine or the (meth)acrylate-functional        alcohol or the glycidyl ether-functional (meth)acrylate and the        carboxyl-terminated polymer of the formula (II) are used in an        amount relative to one another which corresponds to one molecule        of diglycidyl ether or diamine or (meth)acrylate-functional        alcohol or glycidyl ether-functional (meth)acrylate per COOH        group of a molecule of carboxyl-terminated polymer of the        formula (II).

In formula (XV) here, R¹⁰ is a divalent radical and Q¹ is an end groupwhich is selected from the group consisting of the formulae (XVI),(XVI′), (XVI″) and —NH₂.

with the proviso that

Q is —NH— in the case

-   -   in which Q¹ is —NH₂ or the formula (XVI″), and

Q is —O— or the formula (XVII) in the case

-   -   in which Q¹ is the formula (XVI′), and

Q is the formula (XVII) in the case

-   -   in which Q¹ is the formula (XVI).

End group-terminated polymers of the formula (XV) are considered to beespecially the above-described epoxy-terminated polymers of the formula(I), carboxyl-terminated polymers of the formula (II), amine-terminatedpolymers of the formula (XI), (XI′) or (XI″) and(meth)acrylate-terminated polymers of the formula (XII) or (XII′).

The carboxyl-terminated polymers of the formula (II) thus prepared andend group-terminated polymers of the formula (XV) described, especiallythe epoxy-terminated polymers of the formula (I), amine-terminatedpolymers of the formula (XI), (XI′) or (XI″) and(meth)acrylate-terminated polymers of the formula (XII) or (XII′), canbe used as a means of increasing the impact resistance of a polymermatrix and are usable as so-called impact modifiers.

The carboxyl-terminated polymers of the formula (II) and endgroup-terminated polymers of the formula (XV), especiallyepoxy-terminated polymers of the formula (I), amine-terminated polymersof the formula (XI), (XI′) or (XI″) and (meth)acrylate-terminatedpolymers of the formula (XII) or (XII′), are preferably liquid orviscous to highly viscous at room temperature. They are preferablyprocessable by the customary means at least at a temperature of 60° C.Most preferably, they are pourable or at least of honeylike consistencyat least at 60° C. If they are highly viscous or solid, they canoptionally be dissolved, emulsified or dispersed in solvents or resins,such as liquid epoxy resins.

These polymers of the formulae (I), (II), (XI), (XI′), (XI″), (XII) and(XII′) are preferably used in crosslinking compositions, especially insystems into which these polymers can be incorporated by reaction. Thequestion as to the compositions in which these polymers are used thusdepends especially on the polymer matrix. For instance, preference isgiven to using (meth)acrylate-terminated polymers of the formula (XII)or (XII′) especially in (meth)acrylates or unsaturated polyester resinswhich crosslink to a polymer matrix by means of a free-radicallyinitiated or UV light-initiated polymerization reaction.

Epoxy-terminated polymers of the formula (I) and carboxyl-terminatedpolymers of the formula (II) and amine-terminated polymers of theformula (XI), (XI′) or (XI″) are preferably used in epoxy resincompositions.

In the case of the epoxy-terminated polymers of the formula (I), theyare preferably used in the component in which an epoxy resin A ispresent. The epoxy resin A may be a liquid epoxy resin of the formula(IX) or a solid epoxy resin of the formula (VIII). In one embodiment,the composition comprises, as well as an epoxy resin A, a hardener B forepoxy resins, which is activated by elevated temperature. Suchcompositions are used especially as heat-curing epoxy resin adhesivesand cure in the course of heating to a temperature above the heatactivation of the thermally activable hardener B, so as to form a curedcomposition.

In the case of the carboxyl-terminated polymers of the formula (II),they can likewise be used in the component in which an epoxy resin A ispresent.

In the case of the carboxyl-terminated polymers of the formula (II) orof the amine-terminated polymers of the formula (XI), (XI′) or (XI″),they can, however, also be used in a hardener component. Such a hardenercomponent comprises a hardener for epoxy resins, for example polyaminesor polymercaptans. As a result of the mixing of the two components, theyreact with one another, especially also at room temperature, to form acured composition.

Such compositions can be employed widely. Examples thereof areadhesives, sealants, coatings, foams, structural foams, paints,injection resins or coverings. They can be used, for example, inconstruction or civil engineering, in the manufacture or repair ofindustrial goods or consumer goods. They are especially preferably usedas adhesives, especially for bodywork construction and the manufactureof windows, domestic appliances or modes of transport, such as water orland vehicles, preferably automobiles, buses, trucks, trains or ships;or as a sealant for sealing joints, seams or cavities in industrialmanufacture or repair.

Especially preferably, such compositions are used as crash-resistantadhesives, especially for the construction of modes of transport,preferably in the OEM sector of construction of modes of transport.

Additionally preferably, such compositions are used as structuraladhesives for construction and civil engineering, or as highlystressable industrial coatings.

EXAMPLES Raw Materials Used

Hycar ® CTBN 1300X13: acid number = 32 mg/g KOH = 570 meq/kg Mw =approx. 3150 g/mol D.E.R. 331 (bisphenol A diglycidyl ether = 5.40 eq/kg“BADGE”): Mw = approx. 185 g/eq Epilox F-17-00 (bisphenol F diglycidyl5.88 eq/kg ether = “BFDGE”): Mw = approx. 170 g/eq Eurepox RV-H(1,6-hexanediol diglycidyl 6.94 eq/kg ether = “HDDGE”): Bisphenol A: Mw= 228.3 g/mol

Preparation of Carboxyl-Terminated Polymers

Pre-Extended with BADGE (“CTBN-BADGE-CTBN”)

300.0 g (171 meq of COOH) of carboxyl-terminatedacrylo-nitrile/butadiene copolymer (Hycar® CTBN 1300×13) and 7.9 g ofD.E.R. 331 (42.8 meq of epoxy) were weighed into a flanged flask withstirrer, nitrogen inlet and vacuum connection. The mixture was stirredunder gentle vacuum at 180° C. over 3 h. A viscous mass was thusobtained with an acid number of about 23.4 mg/g KOH (approx. 416meq/kg). The product thus obtained was designated CTBN1.

Pre-Extended with HDDGE (“CTBN-HDDGE-CTBN”)

300.0 g (171 meq of COOH) of carboxyl-terminatedacrylo-nitrile/butadiene copolymer (Hycar® CTBN 1300×13), and 4.42 g ofEurepox RV-H (28.5 meq of epoxy) were weighed into a flanged flask withstirrer, nitrogen inlet and vacuum connection. The mixture was stirredunder gentle vacuum at 180° C. over 4 h. A viscous mass was thusobtained with an acid number of about 26.3 mg/g KOH (approx. 468meq/kg). The product thus obtained was designated CTBN2.

Preparation of Epoxy-Terminated Polymers

Terminated with BFDGE (“BFDGE-CTBN-BADGE-CTBN-BFDGE”)

100.0 g (approx. 41.6 meq of COOH) of CTBN1 and 150.0 g (882 meq ofepoxy) of Epilox F 17-00 were weighed into a flanged flask with stirrer,nitrogen inlet and vacuum connection. The mixture was stirred undergentle vacuum at 180° C. over 3 h until a viscous epoxy resin with anepoxide content of approx. 3.36 eq/kg was obtained. The product thusobtained was designated ETBN1.

Terminated with BADGE (“BADGE-CTBN-HDDGE-CTBN-BADGE”)

100.0 g (approx. 46.8 meq of COOH) of CTBN2 and 150.0 g (810 meq ofepoxy) of D.E.R. 331 were weighed into a flanged flask with stirrer,nitrogen inlet and vacuum connection. The mixture was stirred undergentle vacuum at 180° C. over 3 h until a viscous epoxy resin with anepoxide content of approx. 3.05 eq/kg was obtained. The product thusobtained was designated ETBN2.

ETBN1 Post-Extended with Bisphenol A

(“BFDGE-CTBN-BADGE-CTBN-BFDGE-BPA-BFDGE-CTBN-BADGE-CTBN-BFDGE”)

150.0 g (approx. 504 meq of epoxy) of ETBN1 and 7.5 g (approx. 65 meq ofOH) of bisphenol A were weighed into a flanged flask with stirrer,nitrogen inlet and vacuum connection. The mixture was stirred undergentle vacuum at 180° C. over 3 h until a viscous epoxy resin with anepoxide content of approx. 2.78 eq/kg was obtained. The product thusobtained was designated ETBN3.

BADGE-Terminated CTBN (Comparison) (“BADGE-CTBN-BADGE”)

100.0 g (approx. 57 meq of COOH) of carboxyl-terminatedacrylo-nitrile/butadiene copolymer (Hycar® CTBN 1300×13) and 150.0 g(810 meq of EP) of D.E.R. 331 were weighed into a flanged flask withstirrer, nitrogen inlet and vacuum connection. The mixture was stirredunder gentle vacuum at 180° C. over 3 h until a viscous epoxy resin withan epoxide content of approx. 2.99 eq/kg was obtained. The product thusobtained was designated Ref.ETBN.

Efficacy as Impact Modifiers

The epoxy-terminated polymers ETBN1 and ETBN2 and ETBN3 exhibited, inheat-curing epoxy resin adhesives, a marked increase in impactresistance compared to the comparative polymer Ref.ETBN.

Illustrative Compositions

The adhesive compositions Z1, Z2, Z3 and the comparative compositionZRef1 according to table 1 were prepared as follows:

A planetary mixer is initially charged with all components apart fromdicyandiamide and stirred at 90-100° C. under reduced pressure for onehour, then dicyandiamide is added and, after stirring for a further 10minutes, the mixtures is transferred to cartridges.

Preparation of a Pu Prepolymer PUPrep

150 g of Poly-THF 2000 (BASF, OH number 57 mg/g KOH) and 150 Liquiflex H(Krahn, hydroxyl-terminated polybutadiene, OH number 46 mg/g KOH) weredried at 105° C. under reduced pressure for 30 minutes. Once thetemperature had been reduced to 90° C., 61.5 g of isophoronediisocyanate and 0.14 g of dibutyltin dilaurate were added. The reactionwas conducted at 90° C. under reduced pressure until the NCO content hadbecome constant at 3.10% after 2.0 h (calculated NCO content: 3.15%).Subsequently, 96.1 g of cardanol (Cardolite NC-700, Cardolite) wereadded as a blocking agent. The mixture was stirred further at 105° C.under reduced pressure until the NCO content had fallen below 0.1% after3.5 h. The product was used thus as PUPrep.

TABLE 1 Compositions comprising impact modifiers and test results. ZRef1Z1 Z2 Z3 Araldite ® GT 7071 [PW*] 9 9 9 9 BADGE [PW*] 26 26 26 26Polypox R7 (tert-butylphenyl glycidyl 3.0 3.0 3.0 3.0 ether, UPPC) [PW*]Ref.ETBN [PW*] 15.0 ETBN1 [PW*] 15.0 ETBN2 [PW*] 15.0 ETBN3 [PW*] 15.0PUPrep [PW*] 15.0 15.0 15.0 15.0 Dicyandiamide [PW*] 3.2 3.2 3.2 3.2Aerosil ® R 202 (Degussa) [PW*] 7.0 7.0 7.0 7.0 Filler mixture [PW*]13.0 13.0 13.0 13.0 TS [MPa] 31.9 34.7 33.6 34.6 FE at 23° C. [J] 17.218.4 17.6 18.3 FE at −30° C. [J] 4.4 4.6 9.4 4.5 *PW = parts by weight.

Test Methods:

Tensile Strength (TS) (DIN EN ISO 527)

A sample of the composition was pressed to a layer thickness of 2 mmbetween two Teflon papers. Subsequently, the composition was cured at180° C. over 30 minutes. The Teflon papers were removed and thespecimens were punched according to the DIN standard in the hot state.After storage for 1 day, the test specimens were analyzed under standardclimatic conditions with a pulling speed of 2 mm/min.

The tensile strength (“TS”) was determined to DIN EN ISO 527.

Dynamic Resistance to Cleavage (ISO 11343)

The specimens were produced from the compositions described and withelectrolytically galvanized DC04 steel (eloZn) with the dimensions90×20×0.8 mm; the adhesive area was 20×30 mm at a layer thickness of 0.3mm. Curing was effected at 180° C. for 30 min. The dynamic resistance tocleavage was measured in each case at room temperature and at minus 30°C. The impact speed was 2 m/s. The fracture energy (FE) in Joulesreported is the area under the measurement curve (from 25% to 90%, toISO 11343).

1. An epoxy-terminated polymer of the formula (I)

where R¹ is a divalent radical of a carboxyl-terminatedbutadiene/acrylonitrile copolymer CTBN after removal of the terminalcarboxyl groups; and R² is a polyepoxide PEP after removal of n epoxygroups; R^(2′) is H or a radical joined to R²; R³ is a diglycidyl etherDGE after removal of the two glycidyl ether groups; Y¹ and Y² are eachindependently H or methyl; n is 2 to
 4. 2. The epoxy-terminated polymeras claimed in claim 1, wherein R¹ has the formula (IV)

where the broken lines represent the attachment sites of the twocarboxyl groups; b and c are the structural elements which originatefrom butadiene, and a is the structural element which originates fromacrylonitrile; R is a linear or branched alkylene radical having 1 to 6carbon atoms, which is optionally substituted by unsaturated groups; qis 40 to 100; x=0.05-0.3, m=0.5-0.8, p=0.1-0.2; with the proviso thatx+m+p=1.
 3. The epoxy-terminated polymer as claimed in claim 1, whereinR² has the formula (V) or (V′)

where R′, R″ and R′″ are each independently H, methyl or ethyl, z′ is 0or 1 and s′ is 0 or 0.1-12.
 4. The epoxy-terminated polymer as claimedin claim 3, wherein the polyepoxide PEP is bisphenol A diglycidyl ether.5. The epoxy-terminated polymer as claimed in claim 1, wherein thepolyepoxide PEP is diglycidyl ether of the formula (V″) or (V′″)

where r′ is 1 to 9 and d′ is the structural element which originatesfrom ethylene oxide, and e′ is the structural element which originatesfrom propylene oxide; q′ is 0 to 10 and t′ is 0 to 10, with the provisothat the sum of q′ and t′ is ≧1.
 6. The epoxy-terminated polymer asclaimed in claim 5, wherein the polyepoxide PEP is ethylene glycoldiglycidyl ether, butanediol diglycidyl ether or hexanediol diglycidylether.
 7. The epoxy-terminated polymer as claimed in claim 1, wherein R³has the formula (VI) or (VI′)

where R′, R″ and R′″ are each independently H, methyl or ethyl, z is 0or 1 and s is 0 or 0.1-12.
 8. The epoxy-terminated polymer as claimed inclaim 1, wherein the diglycidyl ether DGE is bisphenol F diglycidylether.
 9. The epoxy-terminated polymer as claimed in claim 1, whereinthe diglycidyl ether DGE is a diglycidyl ether of the formula (VI″) or(VI′″)

where r is 1 to 9 and d is the structural element which originates fromethylene oxide, and e is the structural element which originates frompropylene oxide; q is 0 to 10 and t is 0 to 10, with the proviso thatthe sum of q and t is ≧1.
 10. The epoxy-terminated polymer as claimed inclaim 9, wherein the diglycidyl ether DGE is ethylene glycol diglycidylether, butanediol diglycidyl ether or hexanediol diglycidyl ether.
 11. Acarboxyl-terminated polymer of the formula (II)

where R¹ is a divalent radical of a carboxyl-terminatedbutadiene/acrylonitrile copolymer CTBN after removal of the terminalcarboxyl groups; R² is a polyepoxide PEP after removal of n epoxygroups; R^(2′) is H or a radical joined to R²; Y² is H or methyl and nis 2 to
 4. 12. The carboxyl-terminated polymer as claimed in claim 11,wherein R¹ has the formula (IV)

where the broken lines represent the attachment sites of the twocarboxyl groups; b and c are the structural elements which originatefrom butadiene, and a is the structural element which originates fromacrylonitrile; R is a linear or branched alkylene radical having 1 to 6carbon atoms, which is optionally substituted by unsaturated groups; qis 40 to 100; x=0.05-0.3, m=0.5-0.8, p=0.1-0.2; with the proviso thatx+m+p=1.
 13. An amine-terminated polymer of the formula (XI) or (XI′) or(XI″)

where R¹ is a divalent radical of a carboxyl-terminatedbutadiene/acrylonitrile copolymer CTBN after removal of the terminalcarboxyl groups; R² is a polyepoxide PEP after removal of n epoxygroups; R^(2′) is H or a radical joined to R²; Y² is H or methyl and nis 2 to
 4. 14. A (meth)acrylate-terminated polymer of the formula (XII)or (XII′)

where R¹ is a divalent radical of a carboxyl-terminatedbutadiene/acrylonitrile copolymer CTBN after removal of the terminalcarboxyl groups; R² is a polyepoxide PEP after removal of n epoxygroups; R^(2′) is H or a radical joined to R²; Y² is H or methyl; R⁷ isH or methyl; R⁸ is a divalent radical, and n is 2 to
 4. 15. A processfor preparing a carboxyl-terminated polymer as claimed in claim 11 by areaction of a polyepoxide PEP with a carboxyl-terminatedbutadiene/acrylonitrile copolymer CTBN of the formula HOOC—R¹—COOH,wherein the polyepoxide PEP and HOOC—R¹—COOH are used for this reactionin an amount relative to one another which corresponds to astoichiometric ratio of the COOH groups to epoxy groups


16. A process for preparing an epoxy-terminated polymer as claimed inclaim 1 by a reaction of a carboxyl-terminated polymer of the formula(II) with a diglycidyl ether DGE of the formula (III), wherein thepolymer of the formula (II) and the diglycidyl ether of the formula(III) are used for this reaction in an amount relative to one anotherwhich corresponds to a stoichiometric ratio of the glycidyl ether groupsto COOH groups


17. A process for preparing an end group-terminated polymer of theformula (XV)

comprising the following two steps: a) pre-extension, i.e. reaction of apolyepoxide PEP with a stoichiometric excess of a carboxyl-terminatedbutadiene/acrylonitrile copolymer CTBN of the formula HOOC—R¹—COOH togive a carboxyl-terminated polymer of the formula (II)

where R¹ is a divalent radical of a carboxyl-terminatedbutadiene/acrylonitrile copolymer CTBN after removal of the terminalcarboxyl groups; R² is a polyepoxide PEP after removal of n epoxygroups; R^(2′) is H or a radical joined to R²; Y² is H or methyl and nis 2 to 4, in such a way that the polyepoxide PEP and HOOC—R¹—COOH areused in an amount relative to one another such that the ratio of COOHgroups to epoxy groups

where the polyepoxide PEP and the carboxyl-terminatedbutadiene/acrylonitrile copolymer CTBN of the formula HOOC—R¹—COOHshould be selected as described in claim 1; b) termination, i.e.reacting a carboxyl-terminated polymer of the formula (II) with adiglycidyl ether or with a diamine or with a (meth)acrylate-functionalalcohol or with a glycidyl ether-functional (meth)acrylate in such a waythat the diglycidyl ether or the diamine or the(meth)acrylate-functional alcohol or the glycidyl ether-functional(meth)acrylate and the carboxyl-terminated polymer of the formula (II)are used in an amount relative to one another which corresponds to onemolecule of diglycidyl ether or diamine or (meth)acrylate-functionalalcohol or glycidyl ether-functional (meth)acrylate per COOH group of amolecule of carboxyl-terminated polymer of the formula (II); where, informula (XV), R¹⁰ is a divalent radical and Q¹ is an end group which isselected from the group consisting of the formulae (XVI), (XVI′), (XVI″)and —NH₂

with the proviso that Q is —NH— in the case in which Q¹ is —NH₂ or theformula (XVI″), and Q is —O— or the formula (XVII) in the case in whichQ¹ is the formula (XVI′), and Q is the formula (XVII) in the case inwhich Q¹ is the formula (XVI).
 18. A polymer matrix comprising acarboxyl-terminated polymer of the formula (II)

where R¹ is a divalent radical of a carboxyl-terminatedbutadiene/acrylonitrile copolymer CTBN after removal of the terminalcarboxyl groups; R² is a polyepoxide PEP after removal of n epoxygroups; R^(2′) is H or a radical joined to R²; Y² is H or methyl and nis 2 to 4 and an end group-terminated polymer of the formula (XV)prepared by a process as claimed in claim
 17. 19. The polymer matrix asclaimed in claim 18, wherein the polymer matrix is an epoxy resinmatrix.
 20. A composition comprising an amine-terminated polymer of theformula (XI) or (XI′) or (XI″)

where R¹ is a divalent radical of a carboxyl-terminatedbutadiene/acrylonitrile copolymer CTBN after removal of the terminalcarboxyl groups; R² is a polyepoxide PEP after removal of n epoxygroups; R^(2′) is H or a radical joined to R²; Y² is H or methyl and nis 2 to 4 or a (meth)acrylate-terminated polymer of the formula (XII) or(XII′) as claimed in claim
 14. 21. A composition comprising anepoxy-terminated polymer of the formula (I)

where R¹ is a divalent radical of a carboxyl-terminatedbutadiene/acrylonitrile copolymer CTBN after removal of the terminalcarboxyl groups; and R² is a polyepoxide PEP after removal of n epoxygroups; R^(2′) is H or a radical joined to R²; R³ is a diglycidyl etherDGE after removal of the two glycidyl ether groups; Y¹ and Y² are eachindependently H or methyl; n is 2 to 4 or a carboxyl-terminated polymerof the formula (II) as claimed in claim
 11. 22. The composition asclaimed in claim 21, wherein the composition further comprises at leastone epoxy resin A.
 23. The composition as claimed in claim 22, whereinthe composition further comprises a hardener B for epoxy resins, whichis activated by elevated temperature.
 24. A cured composition obtainedfrom a composition as claimed in claim 22 and an addition of a hardenerfor epoxy resins.
 25. A cured composition obtained from heating acomposition as claimed in claim 23 to a temperature above the heatactivation of the thermally activable hardener B.